1. Field
This invention relates to shotguns and is particularly directed to sighting ribs used with such guns.
2. State of the Art
Ventilated ribs have long been used with shotguns and particularly with those used for competitive target shooting. These rib structures have several functions and features which are regarding as desirable by shooters, especially in circumstances requiring repetitive shooting, (which tends to heat the barrel), and competitive or field circumstances which require quick target alignment. These ribs conventionally carry a sighting plane which is approximately flat and planar. The sighting plane may have longitudinal grooves or other features to assist in sighting, culminating in a conventional bead sight at the muzzle end of the gun.
A typical vented rib gun includes a barrel with a longitudinal axis oriented approximately normal the shoulder of a shooter in firing position. The barrel has a muzzle end and a breach end intersected by the longitudinal axis. A rib element which is approximately the same length as the barrel element, but will ordinarily be several inches shorter than the barrel, is mounted atop the barrel with a front end approximately coterminus with the muzzle end and a rear end near but usually somewhat forward of the breach end of the barrel.
Because the rib element is mounted atop the barrel, recoil is directed lower on the shooter's shoulder, away from the shooter's face. Moreover, because of the rib's ventilated structure and its location, the sighting plane carried by the upper surface of the rib element is much less affected by heat than is the barrel; that is, the ventilated rib element overcomes many of the effects of distortion characteristic of shotguns which do not have this feature.
It is desirable for the point of impact of target shotguns at a prescribed sighting range, typically 40 yards, to be several inches higher than the point of aim determined by the plane of the shotgun rib on the relationship of the front and center bead. Accordingly, while the ventilated rib is mounted atop and approximately parallel the longitudinal axis of the barrel, it is typically structured to hold the sighting plane at an attitude sufficiently out of alignment with the longitudinal axis of the barrel to achieve this elevated point of impact. Adjustment of the point of impact at a standard distance is desirable and is provided for in most guns by means for adjusting the elevation of either a rear sight or the front bead sight. Heretofore, however, it has not been practical to adjust the attitude of the sighting plane of a rib element with respect to the longitudinal axis of a barrel. While it has been suggested that the front end of the rib element be mounted in a fashion permitting changes in elevation of the front rib end, efforts to produce a practical gun with that feature have apparently not been successful. It is considered highly desirable for a shotgun to have the capability of adjusting the point of impact with respect to the point of sight at a standard distance. There remains a need in the art to incorporate this feature in high quality shotguns which have ventilated rib elements mounted atop the barrel.